1. Field of the Invention
The present invention relates to a communication method for exchanging data between node terminals, between routers, and between a node terminal and a router, for use in a communication system composed of a pair of networks which are connected by data transmission lines via a gateway and each of which has a plurality of routers each having one or more node terminals. In particular, the present invention relates to a communication method, a communication system, and a gateway used in the communication system that automatically assign addresses to routers and node terminals to reliably send communication data to destinations while significantly increasing the per-unit-time transmission amount.
2. Description of the Related Art
Conventionally, a communication system, such as the one disclosed in Japanese Patent Laid-Open Publication No. Sho 59-62245, is known in which LANs (Local Area Network), each of which allows a plurality of stations to exchange data, are connected via a gateway for data exchange between a pair of LANs.
In the technology disclosed in the above publication, a sender/receiver address specifying the data sender and receiver, as well as the station address indicating the station to or from which data is sent or received and the network address indicating the network to which the station belongs, is added to communication data. During data communication, this address is referenced to reliably send data between LANs even when data is transferred across networks.
However, because there are many types of addresses that are added to communication data used in the conventional communication system described above, a relatively large data description area must be reserved for the address description area within the data communication data. The need to reserve a large data description area prevents per-unit-time data transmission amount from increasing, offering a problem that must be solved.
The communication method, the communication system, and the gateway used in the communication system disclosed in Japanese Patent Laid-Open Publication No. Hei 10-294751 are known as a solution to this problem. The method disclosed in this publication is used in a communication system composed of a pair of networks which are connected by data transmission lines via a gateway and each of which has a plurality of routers each having one or more node terminals. When data is exchanged between node terminals, between routers, and between a node terminal and a router, the router writes the source/destination addresses in the address description area in the communication data in advance and then sends the communication data, in which the source/destination addresses are described, to the destination.
On the other hand, the gateway decodes the source/destination addresses included in the received communication data, checks if the destination and the source are in the same network based on the decoded source/destination addresses and the previously-stored network identification data, selects an appropriate route for the destination of the communication data based on the network identification checking, and then sends the communication data to the destination via the selected route.
Therefore, by simply storing the source/destination addresses in a small address description area provided in the communication data, this method significantly increases the per-unit-time data transmission amount and, at the same time, reliably sends communication data.
However, although the communication method, the communication system, and the gateway used in the communication system disclosed in Japanese Patent Laid-Open Publication No. Hei 10-294751 are used to exchange data between a pair of networks configured in the shape of the numeral 8, no method is disclosed for automatically assigning addresses to the routers and node terminals belonging to each network of the pair.
It is an object of the present invention to provide a communication method, a communication system, and a gateway used in the communication system that can automatically assign addresses to routers and node terminals, check, with the use of the assigned addresses, which network the communication data is to be addressed to, and reliably send the communication data to the destination while significantly increasing the per-unit-time data transmission amount.
To achieve the above object, there is provided a communication method for exchanging data between node terminals, between routers, or between a node terminal and a router using a communication system composed of a pair of networks each comprising a plurality of routers each having one or more the node terminals, the plurality of routers being connected via a first data transmission line, the pair of networks being connected via a pair of routers belonging to the pair of networks respectively and a second data transmission line connecting the pair of routers, the communication method comprising the steps of: causing one of the pair of routers to send into one direction an address assignment frame containing an address value to one of the pair of networks, to assign an address to each router and each node terminal, based on the address value, sequentially from the router, which is nearest to the one of pairs of routers, to the one of pairs of routers itself, and to send the address assignment frame, which has been returned, to the other router of the pair of routers; and causing the other router of the pair of routers to assign the address to itself based on the address value contained in the received address assignment frame, to send the address assignment frame to the other network into the one direction, to assign the address to each router and each node terminal, based on the address value, sequentially from the router which is nearest to the other router, and to return the address assignment frame, which has been returned, to the one of the pair of routers.
According to this invention, one of the pair of routers sends into one direction an address assignment frame containing an address value to one of the pair of networks, assigns an address to each router and each node terminal, based on the address value, sequentially from the router, which is nearest to the one of pairs of routers, to the one of pairs of routers itself, and sends the address assignment frame, which has been returned, to the other router of the pair of routers. The other router of the pair of routers assigns the address to itself based on the address value contained in the received address assignment frame, sends the address assignment frame to the other network into the one direction, assigns the address to each router and each node terminal, based on the address value, sequentially from the router which is nearest to the other router, and returns the address assignment frame, which has been returned, to the one of the pair of routers. Therefore, addresses may be assigned automatically to the routers and the node terminals belonging to the pair of networks.
In a preferred embodiment of the present invention, each of the routers adds at least a destination address to communication data to be sent and sends the communication data containing the destination address to a destination, and each of the pair of routers checks, based on the destination address contained in received communication data and the address assigned to itself, if the destination is included in the network to which the router itself belongs, selects, based on a result of the checking, a route via which the communication data is to be sent, and sends the communication data to the destination via the selected route.
In this mode, each of the routers adds at least a destination address to communication data to be sent and sends the communication data containing the destination address to a destination, and each of the pair of routers checks, based on the destination address contained in received communication data and the address assigned to itself, if the destination is included in the network to which the router itself belongs, selects, based on a result of the checking, a route via which the communication data is to be sent, and sends the communication data to the destination via the selected route. Therefore, communication data may be sent reliably to the destination while significantly increasing the per-unit-time data transmission amount.
In a preferred embodiment of the present invention, when assigning the address to each of the routers and the node terminals, each of the pair of routers increments or decrements the address.
In this mode, because each of the pair of routers increments or decrements the address when assigning the address to each router and each node terminal, it is easily determined which network the destination belongs to by comparing the destination address with the address of the router itself.
To achieve the above object, there is provided a communication system which is composed of a pair of networks each comprising a plurality of routers each having one or more node terminals and in which data is exchanged between the node terminals, between the routers, or between a node terminal and a router, the plurality of routers being connected via a first data transmission line, the pair of networks being connected via a pair of routers belonging to the pair of networks respectively and a second data transmission line connecting the pair of routers, wherein one of the pair of routers has first address assignment means for sending into one direction an address assignment frame containing an address value to one of the pair of networks, for assigning an address to each router and each node terminal, based on the address value, sequentially from the router, which is nearest to the one of pairs of routers, to the one of pairs of routers itself, and for sending the address assignment frame, which has been returned, to the other router of the pair of routers; and wherein the other router of the pair of routers has second address assignment means for assigning the address to itself based on the address value contained in the received address assignment frame, for sending the address assignment frame to the other network into the one direction, for assigning the address to each router and each node terminal, based on the address value, sequentially from the router which is nearest to the other router, and for returning the address assignment frame, which has been returned, to the one of the pair of routers.
According to this invention, the first address assignment means provided by one of the pair of routers sends into one direction an address assignment frame containing an address value to one of the pair of networks, assigns an address to each router and each node terminal, based on the address value, sequentially from the router, which is nearest to the one of pairs of routers, to the one of pairs of routers itself, and sends the address assignment frame, which has been returned, to the other router of the pair of routers. The second address assignment means provided by the other router of the pair of routers assigns the address to itself based on the address value contained in the received address assignment frame, sends the address assignment frame to the other network into the one direction, assigns the address to each router and each node terminal, based on the address value, sequentially from the router which is nearest to the other router, and returns the address assignment frame, which has been returned, to the one of the pair of routers. Therefore, addresses may be assigned automatically to the routers and the node terminals belonging to the pair of networks.
In a preferred embodiment of the present invention, each of the routers has sending means for adding at least a destination address to communication data to be sent and for sending the communication data containing the destination address to a destination, and each of the pair of routers comprises: checking means for checking, based on the destination address contained in received communication data and its own address stored in the storing means, if the destination is included in the network to which the router itself belongs; and route selection means for selecting, based on a result of the checking, a route via which the communication data is to be sent and for sending the communication data to the destination via the selected route.
In this mode, the sending means provided by each of the routers adds at least a destination address to communication data to be sent and sends the communication data containing the destination address to a destination. In each of the pair of routers, the checking means checks, based on the destination address contained in received communication data and its own address stored in the storing means, if the destination is included in the network to which the router itself belongs, and the route selection means selects, based on a result of the checking, a route via- which the communication data is to be sent and sends the communication data to the destination via the selected route. Therefore, communication data may be sent reliably to the destination while significantly increasing the per-unit-time data transmission amount.
In a preferred embodiment of the present invention, when assigning the address to each of the routers and the node terminals, each of the pair of routers increments or decrements the address.
In this mode, because each of the pair of routers increments or decrements the address when assigning the address to each router and each node terminal, it is easily determined which network the destination belongs to by comparing the destination address with the address of the router itself.
To achieve the above object, there is provided a communication method for exchanging data between node terminals, between routers, or between a node terminal and a router using a communication system composed of a pair of networks each comprising a plurality of routers each having one or more the node terminals, the plurality of routers being connected via a data transmission line, the pair of networks being connected via a gateway, the communication method comprising the steps, by the gateway, of sending into one direction an address assignment frame containing an address value to one of the pair of networks; assigning an address to each router, each node terminal, and the gateway itself, based on the address value, sequentially from the router, which is nearest to the gateway, to the gateway itself; sending the address assignment frame to the other route network into the one direction; and assigning the address to each router and each node terminal, based on the address value, sequentially from the router which is nearest to the gateway.
According to this invention, the gateway sends into one direction an address assignment frame containing an address value to one of the pair of networks, assigns an address to each router, each node terminal, and the gateway itself, based on the address value, sequentially from the router, which is nearest to the gateway, to the gateway itself, sends the address assignment frame to the other route network into the one direction, and assigns the address to each router and each node terminal, based on the address value, sequentially from the router which is nearest to the gateway. Therefore, addresses may be assigned to the routers and the node terminals, belonging to the pair of networks, automatically and more speedily.
In a preferred embodiment of the present invention, each of the routers adds at least a destination address to communication data to be sent and sends the communication data containing the destination address to a destination, and the gateway checks, based on the destination address contained in received communication data and the address assigned to the gateway itself, which network the destination belongs to, selects, based on a result of the checking, a route via which the communication data is to be sent, and sends the communication data to the destination via the selected route.
In this mode, each of the routers adds at least a destination address to communication data to be sent and sends the communication data containing the destination address to a destination. The gateway checks, based on the destination address contained in received communication data and the address assigned to the gateway itself, which network the destination belongs to, selects, based on a result of the checking, a route via which the communication data is to be sent, and sends the communication data to the destination via the selected route. Therefore, communication data may be sent reliably to the destination while significantly increasing the per-unit-time data transmission amount.
In a preferred embodiment of the present invention, when assigning the address to each of the routers, each of the node terminals, and the gateway, the gateway increments or decrements the address.
In this mode, because the gateway increments or decrements the address when assigning the address to each router, each node terminal, and to the gateway, it is easily determined which network the destination belongs to by comparing the destination address with the address of the gateway itself.
To achieve the above object, there is provided a communication system which is composed of a pair of networks each comprising a plurality of routers each having one or more node terminals and in which data is exchanged between the node terminals, between the routers, or between a node terminal and a router, the plurality of routers being connected via a data transmission line, the pair of networks being connected via a gateway, wherein the gateway has address assignment means for sending into one direction an address assignment frame containing an address value to one of the pair of networks, for assigning an address to each router, each node terminal, and the gateway itself, based on the address value, sequentially from the router, which is nearest to the gateway, to the gateway itself, for sending the address assignment frame to the other network into the one direction, and for assigning the address to each router and each node terminal, based on the address value, sequentially from the router which is nearest to the gateway.
According to this invention, the address assignment means provided by the gateway sends into one direction an address assignment frame containing an address value to one of the pair of networks, assigns an address to each router, each node terminal, and the gateway itself, based on the address value, sequentially from the router, which is nearest to the gateway, to the gateway itself, sends the address assignment frame to the other network into the one direction, and assigns the address to each router and each node terminal, based on the address value, sequentially from the router which is nearest to the gateway. Therefore, addresses may be assigned to the routers and the node terminals, belonging to the pair of networks, automatically and more speedily.
To achieve the above object, there is provided a gateway for use in a communication system in which a pair of networks, each comprising a plurality of routers each having one or more the node terminals, are connected so that data may be exchanged between the node terminals, between the routers, or between a node terminal and a router, the plurality of routers being connected via a data transmission line, the gateway comprising: address assignment means for sending into one direction an address assignment frame containing an address value to one of the pair of networks, for assigning an address to each router, each node terminal, and the gateway itself, based on the address value, sequentially from the router, which is nearest to the gateway, to the gateway itself, for sending the address assignment frame to the other network into the one direction, and for assigning the address to each router and each node terminal, based on the address value, sequentially from the router which is nearest to the gateway; storing means for storing its own address assigned by the address assignment means; checking means for checking, based on the destination address contained in received communication data and its the own address stored in the storing means, which network the destination belongs to; and route selection means for selecting, based on a result of the checking, a route via which the communication data is to be sent, and for sending the communication data to the destination via the selected route.
According to this invention, the address assignment means sends into one direction an address assignment frame containing an address value to one of the pair of networks, and assigns an address to each router, each node terminal, and the gateway itself, based on the address value, sequentially from the router, which is nearest to the gateway, to the gateway itself. Then the address assignment means sends the address assignment frame to the other network into the one direction, and assigns the address to each router and each node terminal, based on the address value, sequentially from the router which is nearest to the gateway. The checking means checks, based on the destination address contained in received communication data and its the own address stored in the storing means, which network the destination belongs to. The route selection means selects, based on a result of the checking, a route via which the communication data is to be sent, and sends the communication data to the destination via the selected route. Therefore, addresses may be assigned to the routers and the node terminals, belonging to the pair of networks, automatically and more speedily. In addition, communication data may be sent reliably to the destination while significantly increasing the per-unit-time data transmission amount.